STATISTICAL SCIENCE IMPROVING TRANSPORTATION
SIGNIFICANCE
STATISTICAL
With profound effects on communities, safety, public health, and the economy, transportation policy in the public and private
sectors relies on statistical science—from the collection of data to their analysis and understanding to the evaluation of options to the eventual decisionmaking. Gaining an understanding of where, when, and how people travel and how, when, and
where commodities are transported is challenging given the diversity of our society and economy, and this is only the first step
in planning transportation infrastructure and services. Statistical science is also instrumental in formulating effective safety
protocols, determining cost-benefit tradeoffs, and allocating resources while reducing pollution and congestion.
Statistics Plays Important Role in Transportation
DESIGNING COST-EFFECTIVE PUBLIC
TRANSPORTATION SYSTEMS
Before a city, county, or region invests in a
mass transit system, it must be sure the system will serve the needs and budgets of the
community for decades. Statistical science
informs transportation planners through the
entire process, beginning with well-designed
travel surveys to capture specific information about preferred travel mode, travel
purposes, and options. It then relates these
to demographic and lifestyle variables. The
analyzed and aggregated data are used in
ridership forecasts, travel demand models,
and infrastructure investment tools to generate route choices for different travel modes
and enhance urban living by reducing costs.
IMPROVING AUTOMOBILE SAFETY
Highway driving is the most dangerous daily activity most people encounter.
Making driving safer requires sorting
out hundreds of variables to distinguish
driver behavior from vehicle capability
from driving environment. Before policies/
changes such as seatbelts and child car
seats were implemented, it was necessary to have confidence in their effectiveness. Statistical science plays an integral
role during all steps, from the design of
studies to the evaluation of programs.
ADDRESSING PUBLIC HEALTH EFFECTS
Public health is an important consideration
for transportation planners because of the
potential effects of automobile exhaust,
noise pollution, and commute times. Urban
transportation planners collaborate with
statistical scientists and epidemiologists
to evaluate a community’s health risk.
The results may then inform the use and
placement of new roads, bicycle trails,
parks, and connected communities.
the issue, one must take into account factors such as roadway design, traffic light
timing, merging traffic, high-occupancy
vehicle lanes, mass transit, and signage.
Statistical science provides a critical foundaMAINTAINING ECONOMIC VITALITY
tion for data-driven improvements to our
Economic prosperity and employment
transportation system. Statistical methods
growth occur when there is a robust flow
enable planners to construct and validate
of goods on a reliable transportation inframicrosimulations of traffic congestion and
structure. Freight data illustrate the health of explore alternative designs. These models
roads, waterways, railways, airways, ports,
are also useful in planning for emergenand pipelines to ensure a strong transporta- cies, such as managing the evacuation of
tion network. Federal data and freight data
a major city threatened by a hurricane.
at the state, metropolitan, county, and city
levels enable government and private sector
actors to optimize commercial transport.
“Statistical Science Improving Transportation” is part of Statistical
Significance, a series from the American Statistical Association
Decisionmakers use freight statistics as an
documenting the contributions of statistics to our country and
objective baseline to make sound decisociety. For more in this series, visit www.amstat.org/policy/
sions about how to allocate funds, plan
statsig.cfm. The American Statistical Association is the foremost
professional society of statisticians, representing 19,000 scienfor the future, and develop transportation
tists in industry, government, and academia: www.amstat.org.
policies. High quality, timely, and local
This Statistical Significance was produced under the supervision
transportation data thereby helps keep our
of the ASA Transportation Statistics Interest Group.
economy competitive in the global market.
IMPROVING TRAFFIC FLOW
Major urban areas struggle with traffic flow,
particularly during rush hours. To address
2014
Promoting the Practice and Profession of StatisticsTM